As used herein, the phrase “acid labile pharmaceutical agent” refers to any pharmacologically active drug subject to acid-catalyzed degradation. One class of acid labile pharmaceutical agents is a class of antisecretory agents that do not exhibit anticholinergic or H2 histamine antagonistic properties, but that suppress gastric acid secretion by the specific inhibition of the H+, K+-ATPase enzyme system at the secretory surface of the gastric parietal cell (hereinafter “proton pump inhibitors” or “PPIs”). These agents provide a more specific class of inhibitors of gastric acid secretion in mammals, such as humans, by blocking the final step of acid production.
One particular class of PPIs includes substituted benzimidazole compounds that contain a sulfinyl group bridging substituted benzimidazole and pyridine rings. Another class of PPIs is the class of substituted aryl-imidazoles, such as substituted bicyclic aryl-imidazoles. The mechanism of action of the PPIs occurs when they reach parietal cells from the blood and diffuse into the secretory canaliculi, where they become protonated and thereby trapped. The protonated agent is then believed to rearrange to form a sulfenic acid and a sulfenamide. The sulfenamide, in turn, is thought to interact covalently with sulfhydryl groups at critical sites in the extracellular (luminal) domain of the membrane-spanning H+, K+-ATPase. See e.g. Hardman et al., Goodman & Gilman's The Pharmacological Basis of Therapeutics, p. 907, 9th ed. (1996).
Currently available PPI medications have a delay in reaching maximal effect (for example, maintaining a gastric pH above about 3.5) such that it can take approximately five days to reach a steady state effect. Therefore, it would be desirable to have a significant effect on gastric pH before 5 days, beginning with the first dose of the medication.